1. Field of the Invention
Vaccination against both bacterial and viral diseases has been one of the major accomplishments of medicine over the past century. While effective vaccines have been developed for a large number of diseases, the development of safe and effective vaccines for a number of other diseases remains problematic. The use of killed microbial agents as vaccines, although generally safe, will not always be effective if the immunogenic characteristics of the agent are altered. In contrast, the preparation of live, attenuated microbial agents as vaccines will often provide improved immunologic reactivity, but will also increase the risk that the vaccine itself will be infectious, e.g., as a result of reversion, and that the organism will be able to propagate and provide a reservoir for future infection. Thus, although much experience has been gained over the years relating to the preparation of bacterial and viral vaccines, the successful preparation of an effective vaccine against a particular infectious agent can never be assured, even when employing techniques which have been successful for other infectious microorganisms.
Cytomegalovirus (CMV) infection is the leading cause of congenital viral infections, with an incidence averaging 1% of all live births. An additional 5% to 10% of infants acquire CMV perinatally, as a result of mother-to-infant transmission. Although the majority of infants with congenital and perinatal CMV infections are asymptomatic, the disease can be severe and even fatal, usually affecting the salivary glands, brain, kidneys, liver, and lungs. Latent infections by the virus may be subsequently activated by pregnancy, multiple blood transfusions, or immunosuppression for organ transplantation. For that reason, it would be desirable to provide a safe, effective and economic vaccine capable of affording protection against cytomegalovirus infections, particularly for women of child bearing age to avoid transmission of the disease to their children and for immunosuppressed individuals for whom CMV infection can be fatal.
2. Description of the Prior Art
Pereira et al. (1982) Infect. Immun. 36:924-932 describe the preparation of a panel of monoclonal antibodies specific for three antigenically distinct groups of cytomegalovirus glycoproteins, including glycoprotein A as the present invention. See also, Pereira et al. (1983) Infect. Immun. 39:100-108 which describes the electrophoretic properties of at least 11 polypeptides immune precipitated from sera of children infected by CMV infection.